Some conservatives are arguing that President Obama's weakness and indecision forecast American failure--and that, if we're going to fail, we should just get out now...

Some Republicans are understandably dismayed at the prospect of supporting a war they worry this president is incapable of prosecuting with sufficient vigor or conviction. They argue that keeping faith with the troops requires rejecting any halfhearted approach. They are right that Americans who wish to support our troops in the field should not accept policies that deprive them of the means to win. But a turn by Republicans to rhetorical opposition to the war would only absolve the Obama administration of its Afghan duty. The better course is to push the administration to take responsibility for the outcome in Afghanistan by continuing to support a fully resourced war effort, while criticizing and opposing any decisions that undermine the troops' chance of success...

A model for Republicans is the behavior of Senator John McCain from 2003 to 2007. McCain consistently questioned, challenged, and criticized President Bush's strategy and tactics in Iraq, but he never wavered in his determination to do everything possible to succeed there.

No need for me to repeat how much I admire McCain. But if things get worse in Afghanistan as election day gets closer, will the GOP be tempted to take advantage?

Not impossible, but I think most Republicans feel that they were ultimately vindicated on Iraq, so backstopping the "war of necessity" is a much easier call.